"A [preacher] who does not love art, poetry, music and nature can be dangerous. Blindness and deafness toward the beautiful are not incidental; they are necessarily reflected in his [preaching]." — BXVI

Only thing I can figure is that it is foolish to wage a war with two fronts, especially when they would require different tactics. Aside from what appears to be a de facto sede vacante strain in certain areas, the SSPX appears to be just fine. Once canonically integrated, they could be left to their own devices and go about the business of saving souls.

The other front is much more dangerous territory and will be harder to deal with, IMO. I could see where we would want to shore up the easier of the two fronts first.

Someone said, half-joking, that next the various other bishops have to sign something accepting Trent.